Automated liquid penetrant inspection system

ABSTRACT

A system of in situ inspection of critical jet engine parts for defects by applying a high penetrating fluorescent oil and inspecting under a light of the proper wavelength. The system which is unitized and portable includes an evacuatable chamber suitable for containing the parts to be inspected. A series of tanks containing the pressurized solutions of penetrant emulsifier wash and developer as well as a hot-air tank are operatively connected to the chamber so that the required solution can be applied under proper conditions for the necessary time period to thereby disclose any defect in the critical engine part.

United States Patent Mendoza Oct. 2, 1973 AUTOMATED LIQUID PENETRANTINSPECTION SYSTEM Emilio Mendoza, 5018 Northfield Drive, San Antonio,Tex. 78228 Filed: Feb. 23, 1971 Appl. No.: 118,010

Inventor:

U.S. Cl. 73/104, 118/9 Int. Cl. G0lb 5/28, GOln 19/08 Field of Search118/7, 9; 73/104 H1966 Weiskopf 1 134/95 H1968 Du Grail 134/95 VA C U UMPUMP Primary Examiner-Herbert Goldstein Attorney-Harry A. Herbert, Jr.and Arsen Tashjian [57] ABSTRACT A system of in situ inspection ofcritical jet engine parts for defects by applying a high penetratingfluorescent oil and inspecting under a light of the proper wavelength.The system which is unitized and portable includes an evacuatablechamber suitable for containing the parts to be inspected. A series oftanks containing the pressurized solutions of penetrant emulsifier washand developer as well as a hot-air tank are operatively connected to thechamber so that the required solution can be applied under properconditions for the necessary time period to thereby disclose any defectin the critical engine part.

1 Claim, 1 Drawing Figure inc PEA/f TIP/7N 7 a: 33 211-6 pit/E4 aria?PATENTED 5 3.762216 :12- P5; rm/vr ELEC' 3! a: 2&6 Diva aPiJ? VA C UUMPUMP INVENTOR. [M141 4 Mia/n02 AUTOMATED LIQUID PENETRANT INSPECTIONSYSTEM BACKGROUND OF THE INVENTION The invention relates to a unitizedportable in situ inspection system for conducting penetration dyet'estson metal parts and assemblies at any convenient location rather than atthe fixed location of the testing equipment.

Certain critical parts such as turbine and compressor blades for jetengines require extremely careful inspection for locating possibledefects such as cracks. A common method of performing this criticalinspection is called the liquid penetrant method." The principleinvolved includes the application of a high penetrating fluorescent oilon the part. The oil will penetrate into any defects such as crackswhich may be present on the surface of the part. The excess oil is thenremoved and a light of the proper wavelength is directed on the partmaking any defects which may be present readily detectable.

The above-described method involves the use of certain chemicals and,although they generally remain on the part a very short time, the timeis very critical for the successful detection of minute defects. Thepresent method of performing this inspection is through the use ofcostly conveyor systems and highly complex electronic control equipment.Generally, four tanks are placed in a line for servicing the conveyorsystem. The tanks contain penetrant, emulsifier, wash and developer. Ifeach tank is assumed to be 3 feet long, a floor space of approximately27 linear feet is required to set up and operate an automated inspectionsystem utilizing presently available equipment.

It can be seen that it would be most desirable to eliminate all of thecostly material handling equipment and complex electronic timingapparatus. This can be accomplished by providing a system wherein theparts being inspected are kept stationary or fixed and the solutions arepiped in. Also, by using pressurized solutions, good coverage is insuredand the critical timing can be achieved much more easily than by anypresently known systems. Thus, a great saving in equipment, skills andtime, as well as increased reliability would be realized.

SUMMARY OF THE INVENTION The present invention is concerned withproviding a highly reliable system wherein critical parts can beinspected for surface defects by the use of a high penetratingfluorescent oil. A unitized portable system including a container forholding the parts to be inspected and the required chemicals arecombined into a single apparatus which quickly and easily makes thenecessary tests and provides the results with a minimum expenditure oftime and effort.

Accordingly, it is an object of the present invention to provide asimple unitized portable apparatus for performing in situ tests by theliquid penetrant method on jet engine parts or the like.

Another object of the invention is to provide an automated system forinspecting large numbers of relatively small engine parts such asturbine and compressor blades by piping in the solutions to a containerunder vacuum which holds the parts to be tested.

Still another object of the invention is to provide a method forperforming liquid penetrant tests on engine parts which will eliminatethe use of costly conveying equipment by utilizing an automated in situsystem. The system requires comparatively simple timing apparatus whichis precise and reliable.

A further object of the invention is to provide a liquid penetranttesting system wherein the penetrant, emulsifier, wash, and developerfluids are stored under pressure in tanks operatively connected to acontainer for holding the parts to be tested. This system allows thesolutions to be applied with full uniformity and with the requiredprecise timing.

A still further object of the invention is to provide an automatedliquid penetrant inspection system utilizing readily availablecomponents which can be easily assembled and which can be operated bypersonnel with a minimum of technical skills while at the same timeproducing results quickly with complete reliability.

These and other objects, features and advantages will become moreapparent after considering the following detailed description taken inconjunction with the illustrative embodiment in the accompanyingdrawing.

DESCRIPTION OF THE DRAWING The FIGURE is a view in schematic of anautomated liquid penetrant inspection system according to the inventionshowing the unitized and portable nature of the system.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the FIGURE, thereis shown a schematic view of the automated inspection system. The partsto be inspected are housed in the chamber 13. A series of nozzles 15 arepositioned at locations in the wall of the chamber or container 13preferably at each corner. A manifold element 17 serves to carry varioussolutions to conduits 19 in the wall of container 13 and to the nozzles15 attached thereto. The container 13 in which the parts to be inspectedare held may be vacated by lowering to below atmospheric pressure forimproved results during the operation of the various steps required tomake the tests.

A series of pressure vessels are operatively attached to the manifold 17through a corresponding series of electrically operated valves. Thefirst pressure vessel 21 contains a solution of penetrant which isapplied to the part in the chamber 13 by opening the valve 23. A secondpressure vessel 25 contains an emulsifier which is applied to the partwhen the valve 27 is opened. After these procedures, the third pressurevessel 29 containing a wash solution is caused to be injected throughthe nozzles 15 to the chamber 13 when the valve 31 is electricallyopened. A fourth pressure vessel 33 which contains a developer isconnected to the manifold 17 through the valve 35 for the purpose ofapplying the solution to the part to be inspected in the container 13.The part is then caused to be dried by the application of hot air fromthe fifth pressure vessel 37 when the valve 39 is opened.

The valves 23, 27, 31, 35, and 39 are controlled by the panel 41 whichis connected to the several valves by the lead wires 43. Since eachvalve is grounded, the circuit to any one particular valve is completedwhen the internal connections (not 51 within the control panel 47 aregrounded. Any appropriate timing circuitry can be added if desired toprecisely time each particular spraying operation.

MODE OF OPERATION In operation, the parts to be inspected are placed inthe chamber 13. In order to obtain better results, the chamber 13 can beevacuated prior to the application of some of the solutions. The firstvalve 23 is caused to be opened by pushing the appropriate button on thecontrol panel 41. This allows the penetrant in the first pressure vessel21 to enter the manifold element 17 and then pass to the conduits 19 andemerge from the nozzles as a spray and impinge on the part to beinspected in the chamber 13. After passage of a predetermined timeinterval, valve 23 is closed and the penetrant is allowed to remain onthe part. Then the second valve 27 is caused to be opened allowing theemulsifier to flow into the manifold 17 from the second pressure vessel25. This solution also flows into the conduits l9 and through thenozzles 15 onto the part being inspected. After the proper amount ofemulsifier has been applied, the second valve 27 closes.

The emulsifier remains on the test part for a predetermined time andthen the third valve 31 is caused to be opened allowing a wash solutionfrom the third pressure vessel 29 to enter the manifold 17, pass throughthe conduits 19 and emerge from the nozzles 15. The test part is thuswashed clean of the excess penetrant and emulsifier. The next step inthe inspection process involves the application of developer to thewashed test piece. This is accomplished by causing the fourth valve 35to open and allowing the developer to enter the manifold 17 from thefourth pressure vessel 33. The developer is sprayed on the test piece inthe chamber 13 and after the passage of the proper time interval thevalve 35 is closed and any defects on the part to be inspected begin tobecome visible. The test piece is then dried by the application of hotair from the fifth pressure vessel 37 when the fifth valve 39 is openedand the hot air passes through the manifold 17, the conduits 19 and thespray nozzles 15. After the test piece has dried, the vacuum in thechamber 13 is destroyed and the part is ready for inspection.

In practice, the solutions are fed to the spraying nozzles 15 forspecific predetermined time intervals which are controlled eithermechanically or electrically. The container or chamber 13 is generallydesigned around the parts to be inspected and a basket of blades can behandled by a 36 inch cubic box constructed of either transparent plasticor sheet metal. For best results in applying the penetrant andemulsifier and also drying the parts after the wash cycle, the chamber13 should be evacuated. The vacuum pressure can be determinedexperimentally for the specific part being processed.

Although the invention has been illustrated in the accompanying drawingand described in the foregoing specification in terms of a preferredembodiment thereof, the invention is not limited to this embodiment orto the preferred configuration mentioned. It will be apparent to thoseskilled in the art that my invention can be practiced by utilizing othersolutions in the pressure vessels such as an additional tank forcleaning solution and freon can be used as a carrier. Also, it should beunderstood that various changes, alterations, modifications andsubstitutions, particularly with respect to the construction details canbe made in the arrangement of the several elements without departingfrom the true spirit and scope of the amended claims.

Having thus described my invention, what I claim and desire to secure byLetters Patent of the United States 1. An improved unitized automatedliquid penetrant inspection system for in situ testing of parts,comprising, in combination, a chamber for holding parts to be tested,vacuum pump means for evacuating said chamber to a predeterminednegative pressure, a plurality of nozzles positioned on the inner wallof said chamber, a conduit operatively connecting said nozzles to eachother, a manifold element having a plurality of inlets and a singleoutlet, the outlet of said manifold being operatively connected to saidconduit, a plurality of pressure vessels each having an outlet connectedto a separate inlet in said manifold element, one of said pressurevessels containing penetrant, another of said pressure vesselscontaining emulsifier, another of said pressure vessels containingwashing solution, another of said pressure vessels containing developer,and another of said pressure vessels containing hot air, an electricallycontrolled valve positioned between the outlet of each of said pressurevessels and the corresponding inlet in said manifold element, and meansfor selectively controlling the flow of material from each of thepressure vessels through the manifold element to the conduit and nozzlesin said evacuated chamber so as to impinge on the parts to be tested ina predetermined sequence for a predetermined time interval.

1. An improved unitized automated liquid penetrant inspection system forin situ testing of parts, comprising, in combination, a chamber forholding parts to be tested, vacuum pump means for evacuating saidchamber to a predetermined negative pressure, a plurality of nozzlespositioned on the inner wall of said chamber, a conduit operativelyconnecting said nozzles to each other, a manifold element having aplurality of inlets and a single outlet, the outlet of said manifoldbeing operatively connected to said conduit, a plurality of pressurevessels each having an outlet connected to a separate inlet in saidmanifold element, one of said pressure vessels containing penetrant,another of said pressure vessels containing emulsifier, another of saidpressUre vessels containing washing solution, another of said pressurevessels containing developer, and another of said pressure vesselscontaining hot air, an electrically controlled valve positioned betweenthe outlet of each of said pressure vessels and the corresponding inletin said manifold element, and means for selectively controlling the flowof material from each of the pressure vessels through the manifoldelement to the conduit and nozzles in said evacuated chamber so as toimpinge on the parts to be tested in a predetermined sequence for apredetermined time interval.